Process of producing toxic material



UNITED STATES PATENT GFFICE PROCESS OF PRODUCING TOXIC MATERIAL J acquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia N Drawing. ,Application August 7, 1941, Serial No. 405,889

14 Claims.

This invention relates to the production of wood preservatives and solvents from tars, fractions and residues derived therefrom, and to controlling thetoxicity and general characteristics of said wood preservatives, and the general charinventory rather than moving to trade channels, acteristics of said solvents. or at best, in some instances, be sold at distress This application is a continuation in part of prices. application Serial No. 352,674, filed August 14, Many proposals have been brought forward 1940, Process of producing toxic material, 00- for the lowering of the cost of coal tar wood pending herewith, as to all matter common to the preservatives- One of the m r on s bein the two applications. dilution of the coal tar preservative with a cheap Suitable starting materials for practicing the petroleum oil; however, when a coal tar product present invention comprise tars derived from is diluted with a petroleum product, as for inwood, coal and petroleum and gas containing stance a gas oil, or higher boiling petroleum carbon; residues and fractions thereof, and more p the Overall toxicity 0f the mixture is not specifically, heavy hydrocarbons from whatever such as might be expected by calculation of the source derived capable of having toxicity and toxicity and percentages of the constituents of solvency induced therein as more fully set forth the mi instance. if 009,1 tar having a in the following. toxic value of X is placed in mixture with a An object of the invention is the controlling of petroleum product having substantially no toxic toxicity inducing conditions and boiling ranges of value-the mixture being equal parts-it would the wood preservatives of the present invention be e p e t t e resultant tu e W0u1d as produced from the named starting materials, have a toxic value of X. Such, however, is or the like. Other objects of the invention will not he case. The mix ure has a toxic value appear from the following disclosures. lower than /2 X due to the toxicity blanketing Coal tar is at present one of the most widely effect 0f the petroleum P used wood preservatives. The generally accepted Thus. in Summarizing the Coal tar Wood P method of wood preservation by coal tar or coal Serving industry. t can be Said that in tar products is by allowing said coal tar or coal tempts to distill 0091 for the production of l tar roducts to penetrate the interstices or cells l w residue creosote. an in rd n te amount of of the wood; as for instance by soaking, brushpitch iS Produced h at times, must b 8016- in ing, dipping, spraying and pressure impregnatio a distress market, (2) in attempts to use coal tar, of the wood by the coal tar wood preservative; as such, as a wood preservative, severe and at by far the most common practice, however, is th times impracticable treating conditions must be pressure impregnation. imposed on, and employed by, the equipment to For impregnation of wood by preservatives, at secure good penetration of the wood and (3) in times coal tar, as such, is employed, but because attempts to lower the cost of the coal tar wood of its physical characteristics such as high boiling p v v y dilution W e Petroleum p fractions, coke residue, viscosity, free carbon, inuct,.toxicity is sacrificed; also (4) in attempts to soluble in benzol or the like, etc., coal tar as a recover all creosote possible from a en coal wood preservative of high quality and cleanlines tar, that is, by distilling the tar to substantial leaves much to be desired. dryness, the resultant creosote has such a high Coal tar creosote which is a distillate recovered es above thet it is not universally from coal tar is widely used as a wood preservaacceptable as a high grade e s e. tive, and may be recovered from coal tar in the I11 aficerdence With the foregoing sures, it order of 60% to 70%, but such a creosotehas an h s lon b a desideretum in the art to p inordinately high residue above 355 C., and induce from the tars, and especially coal tar or the asmuch as some creosote users prefer a much v um of acceptable WOOd preservative lower residue above 355 C., creosote representwhich more closely pp e equal exceed ing 60% to 70% of coal tar is not readily acceptthe original volumes of the crude tars, and, in the able as a high grade creosote. Thus to produce Case Of tars miXed With Petroleum p to a high grade creosote from coal tar, that is to provide a method o eliminating or c e sing say, having an acceptable residue above 355 C., the toxicity blanketing effect of the petroleum for example 20%, the recovery of creosote mustfraction when present in admixture with toxic be restricted to in the order of 35% down to 25% tars; and .to provide a method for inducing or even lower. Because of, at times, the distress condition of the pitch market, inordinate hardships are imposed on the coal tar industry by recoveries of only from 25% to 35% of creosote from coal tar for the reason that to pitch thus produced must, at times, be placed in toxicity in hydrocarbons substantially void of toxicity.

The following examples will serve to illustrate several ways of practicing the present invention, but not in the sense of implying restrictions.

Example 1.Coal tar is distilled to yield in .the order of 65% distillate, which in the trade is termed creosote, but, because this creosote distillate has in the order of 40-50% residue above 355 0., its use is precluded from trade channels as comparison with conventional creosote is concerned; too, its boiling range, precludes it from entering trade channels using creosote as it has an initial boiling point above 355 C.

Attempts at cracking such high residue to produce acceptable creosote fail to give commercial returns, as coke and gas form major products.

By the process of the present invention said high residue is mixed with or without heat, with approximately of its volume of a petroleum oil having a distillation range desirably comparable with or coinciding at some point with a boiling point or points of the high residue, as for instance and in this specific example a petroleum gas oil type boiling between 300 C. and 450 C. Said mixture is then distilled under reduced, atmospheric or superatmospheric pressure, the vapors being led to a toxicity inducing chamber, said toxicity inducing chamber being adapted to be and is heated to from 300 C. to 750 C. By thermal action on said vapors, toxicity is induced and the boiling range of the condensed product is, by control of the heat in .the toxicity inducing chamber and time of contact or retention of vapors therein and/or percentage of petroleum oil, reduced to include the boiling range of any of the standard Wood preservatives, as for instance a shingle stain creosote oil boiling from 140 C. to 350 C., or a high grade creosote of American Wood Preservers Association identification boiling, say not substantially more than 10% at 210 C. and having a residue at 355 C. that is permissible, as an example, not less than zero per cent and not more than substantially 50%.

Products thus obtained are more toxic to wood destroying agencies than either of the components of the starting material, or the mixture.

Time of retention of the vapors in the toxicity inducing chamber is exceedingly diflicult to state in fixed time limits, and moreover, is not at all necessary. The time required is determined by correlating the temperature with vapor retention time to the end that toxicity and desired boiling ranges are induced and may be determined by tests of samples withdrawn. Generally stated, other things being equal, the longer the retention period, the greater the amount of so-called permanent gases produced; thus, it becomes expedient to regulate the retention time to only that necessary for the inducing of toxicity and desired boiling range. ducing chambers of displacements similar to that of the distillation unit may be employed; howranges substantially lower than those acceptable in the wood preservative; or the condensed product may be fractionated to produce a high, low and intermediate boiling wood preservative.

The distillation unit may be operated at atmospheric, reduced or superatmospheric pressure and said pressure conditions may extend to the toxicity inducing chamber if desired, or the pressure conditions in the distillation and toxicity inducing units may be operated independently.

In the event the desired boiling ranges and desired toxicity have not been induced in the product after one passage through the toxicity inducing chamber, a portion or all of the efliuent product may be returned to the still and vaporized for further thermal treatment, one or more times as required.

Example 2.It has long been desired to impregnate wood with coal tar, as such, and a few consumers of coal tar wood preservatives do use partially refined coal tar; however, the severe conditions imposed in the treating equipment place the use of straight coal tar as a wood impregnant in the category of questionable practice.

By the process of the present invention, coal tar or the like is mixed with a high boiling fraction from petroleum, as for instance a refined fuel oil, in the amounts of one part coal tar or less, and one part or more of fuel oil. The mixture is then heated if desired to promote solubility and agitated whereby to produce as a sedi ment, capable of removal by known means, mass high in carbon containing insoluble in benzol fractions and free carbon material originally retained in said tar. The supernatant liquid is then removed in any suitable manner from the residue which is discarded; the supernatant liquid, that is, the refined coal tar and the fuel oil, is then distilled, the vapors being led to the toxicity inducing chamber wherein said vapors are subjected to the thermalizing eifect of a temperature from 300 C. to 750 C. whereby to I induce toxicity and desired boiling range of the Toxicity in-;

toxicity inducing chamber, they may be used in toto as the wood preservative, in which case it is not advisable to induce boiling point or wood preservativesought, as for instance containing the boiling range of any of the preservatives named in the foregoing or others. The vapors are condensed and thus include the wood preservative whose boiling range and toxicity are, among other things, dependent on the temperature and time of retention of the said vapors in the toxicity inducing chamber. Contact metals and/or materials-placed in the toxicity inducing chamber may also assist in the reduction of viscosity, lowering of specific gravity and/or inducing of toxicity and production of the desired boiling range in the condensed product flowing from the practice of the process of the present invention.

By the proper control of the process variables, including rate and amount of distillation, time and temperature of vapors in the toxicity inducing chamber, the desired initial boiling point and the residue above 355 C. may be secured.

However, if an initial boiling point lower than a specification wood preservative be produced, the inadmissible low boiling ends may be removed and used as solvents, thus leaving the Wood preservative having specification low ends.

Other things being equal, in the selection of the high boiling oil or high boiling petroleum fraction relatively rich in hydrogen to mix with the coal tar, or fraction thereof, and other materials, the higher the end point of said high boiling oil or high boiling petroleum fraction, the greater will be the percentage of tar, fractions thereof, or. other material vaporized for subsequent passage to toxicity inducing chamber. However, there may be no great wisdom under certain conditions in having its boiling range such that portions of it remain in the still after the tar or fraction thereof has been completely vaporized, or as much vaporized as is required.

The toxicity inducing chamber may be heated by any convenient means and, if desired, may be filled with, or partially filled with contact material such as earths and metals; alloys or metallic compounds which serve to promote toxicity induction; all metals, alloys, compounds, as bars, shapes or pellets, metals or forms or compounds of metals deposited on carriers, earths and gels which do not cause serious deposition of carbon thereon when subjected to operating conditions named.

In the foregoing examples all vapors have been shown as being conducted to an indicated single toxicity inducing chamber. At times having more than one chamber, or in lieu thereof, the means for regulation of the temperature in said single chamber may be desirable under certain conditions; under conditions where the starting materials have wide distillation range, it may be desirable to subject various portions of the vapors to varying degrees of heat. This of course, as stated may be accomplished with a single chamber adapted to carry varying degrees of heat, or by having several chambers carrying varying degrees of heat to which the vapors are led.

Example Zia-Petroleum oils are, in general, notoriously poor wood preservatives. During the recovery of salable fractions from crude petroleum, there are at times heavy refinery residues of liquid and solid nature which contain condensed ring structures. The residues, as such, have little or no toxicity to make them fit for use as a wood preservative. v

By the process of the present invention, these refinery residues may be mixed in equal volume, or more or less, with a, high boiling petroleum fraction containing, if desired, a percentage boiling within the range of a boiling point or points of said residue and distilled, the distillate traversing a toxicity inducing chamber heated to from 300 C. to 750 C. and the vapors condensed. The condensed product will have a toxicity to wood destroying agencies greater than the starting material or the component parts thereof. By control of process variables including percentage of the starting material distilled, temperature of the toxicity inducing chamber, the time of retention of vapors in the toxicity inducing chamber and the percentage of materials utilized, the boiling range and toxicity of the condensed vapors may be controlled. The mixing of equal parts of the refinery residue having condensed ring structure with a high boiling petroleum product is for the purpose of illustrating percentages; other percentages may be used, as for instance the refinery residue having condensed ring structure may represent '7 or more of the mixture.

Looked at in one way, suitable starting materials include those carbonaceous materials having condensed ring structures, which statement includes those materials having constituent parts which may be viewed as a multiplicity of rings, or multiple structures that may form ring multiples,

"Concerning the degree of recovery of the mixtures to be distilled, that is to say, the percentage to be vaporized, the distillation may be carried forward to where all .possible material is vaporized, and, as stated, other things being equal, the inclusion of oils relatively rich in hydrogen capable of distilling at a high degree of heat without substantial residue assists in greater production of vapors for subsequent passage to the toxicity inducing chamber. To assist the distillation, vapors or gases, including saturated or superheated steam, of extraneous source may be blown or bubbled through the mass distilling.

The material being distilled for production of Vapors to be led to the toxicity inducing chamber, may be distilled to that degree that conforms to the character of desired material, that is to say, if it is desired to produce a Wood preservative having no substantial residue above 355 (3., then the distillation would be carried to that point; of course, consideration being given to possible subsequent changes in boiling points in the thermal chamber.

Regarding the percentage of high boiling oils to be mixed with the tars, fractions thereof and refinery residues, it is difficult to state exact percentages inasmuch as said tars, fractions thereof and refinery residues are of constantly varying composition, and the degree of heat treatment varies in accordance with the end material required. As little as 5% or less of the added oil relatively rich in hydrogen has proven beneficial and as great as volume for volume, or more, is permissible under certain conditions.

As examples of substantially or relatively nontoxicpetroleum oils may be mentioned cracking coal tar, cracked residuum, flashed residuum, various so-called aromatic extracts, reduced crudes, fuel oils, topped crudes, benzine, gasoline, kerosene, furnace oils, etc.

For some reason aromatic fractions of petroleum oils do not provide lethal concentrations as would be expected from their aromatic content.

The substantially or relatively non-toxic petroleum fractions usable in the present process include those named and any others rich in hydrogen.

The toxicity inducing chamber may be of any design chosen, the major consideration being that said chamber be adapted for the vapors to traverse same while being controllably heated with time of passage regulated. As stated, contact materials, such as metals and their compounds may be placed in the chamber; said materials including any not adapted to cause serious carbon deposition thereon or in the chamber under process conditions; among the metals and their compounds usable are aluminum, molybdenum, chromium, magnesium, cobalt, iron, nickel, copper, separately or as alloys, or as compounds.

In Example 2 was mentioned the inclusion of a sedimenting step; instead of allowing the fraction high in carbon to settle out by gravity, it may be removed as by centrifuging or filtering, and this step of removing a fraction or fractions high in carbon may be included in all examplesor it may be omitted from all examples.

The term coal tar is meant to include gas house tar, and in general to include all tars derived from coal or the like, including low temperature tar and solvent extracts of coal.

In accordance with the present invention, wood preservatives of varying boiling ranges including shingle stain oils may be produced, and the process may be controlled so as to produce oils conforming in their boiling range to A. W.'P. A. creosote, that is to say as for instance, not more than substantially 5% distilling at 210 (3., or a shingle stain creosote oil as per Neville "1938 specifica tions boiling entirely between 140 C. and 350 C., or a wood preservative oil as specified by Prussian State Railways, boiling not more than 3% at 150 C., or others of specifications of record.

The scope of the present invention broadly covers inducing toxicity in materials having substantially no toxicity; enhancing toxicity in those materials having toxicity, as for instance certain tars, by subjecting at least a portion of said materials in the vaporous phase to toxicity inducing conditions as aforestated, while contacting the vapors of an oil of dissimilar characteristics.

In the foregoing, tar has been named as one of the starting materials of the process of the present invention. At times it may be advisable to recover only a portion of the tar--or fraction when used as a starting materialas vaporous material for treatment in the toxicity inducing chamber, thus leaving a portion of tar in the still as pitch, or the like, for withdrawal and subsequent use or disposition. In practicing this form of the present invention, a tar may be mixed with a. portion of petroleum oil or any oil relatively rich in hydrogen whose end point substantially approximates the highest boiling point of the tar it is desire to vaporize, that is to say, the highest boiling point of the recovered vapors of the tar. Said mixture is vaporized up to a temperature conforming substantially to the end point of the oil relatively rich in hydrogen and the vapors of the mixture subjected to toxicity inducing conditions as stated in the foregoing. Thus may be produced a residue or pitch substantially free from contamination of the petroleum product. The example and condition just stated is for purposes of illustration only and is not to be construed as a limitation.

Any petroleum product or oil relatively rich in hydrogen of the correct boiling range, liquid at the operating temperature of the process, and coming within the scope of the disclosures made, may be employed for any of the indicated purposes.

In the specification and in the appended claims, the expression condensed ring structure or multiplicity of rings is meant to include that material containing fractions of cyclic nature produced by pyrogenetic decomposition and/or catalytic action on oils of substantially parafiinic and/or asphaltic nature, as for instance petroleum or fractions thereof,

The products of the process of the present invention and especially those of the lower boiling range, may be used as solvents and thinners, with or without subsequent refining; however, the entire range of the products may be used for certain purposes.

By the process of the present invention, it will be found that toxic wood preservative may be had from any of the tars or fractions thereof aforementioned.

The present invention is, among other things, primarily concerned with a novel method whereby increased yields of wood preservatives of certain grades are made possible from tar or tar derivatives, and is characterized among other things, by providing said increment of wood preservative from tar fractions outside the range usually accepted for toxicity measurement. In other words, the increased yield of wood preservative of the present invention from tars or derivatives thereof, stems from converting those tar fractions, or tar derivative fractions boiling substantially above 270 C. into more toxic substance whereby to increase total wood preservative yield.

The toxicity of a tar derived wood preservative is generally based on its percentage boiling at 270 C., thus it becomes an object of the present invention to increase the percentage of tar derived wood preservatives boiling at and adjacent to 270 C. or below, by impressing the conditions of the present invention on crude and/or refined wood preservatives and/or tars, or fractions thereof.

Looked at another way, the present invention also may provide a process for converting tar, fractions thereof or wood preserving fractions boiling above 270 C. to substances of lower boiling range, including an additional percentage .boiling below 270 C., whereby to induce toxicity and at times to provide a greater percentage of fractions boiling at any given point as compared to a simple distillation on the starting materials of the process.

Other objects of the invention will become apparent from the following disclosures.

By the process of the present invention, wood preservatives conforming to any of the following distillation specifications may be made, although it is to be strictly understood that the specifications are not restrictions on the productive ability of the process; the present invention inerely being circumscribed by those wood preserving products of possible manufacture by the present process.

WOOD PBESERVING IMPBEGNANTS Specifications 1. A. W. P. A.

Up to 210 C., not more than 5% Up to 235 C., not more than 25% P. A. Up to 210 C., not more than 1% Up to 235 C., not more than 10% Up to 355 C., not less than 65% 3. A. W. P. A.

a. Up to 235 C., not more than 1 b. Up to 300 C., not more than 16 /2% c. Up to 355 C., not less than 45% 4. A. W. P. A.

a. Up to 210 C., not more than 8% 17. Up to 235 C., not more than 35% 5. A. W. P. A.

a. Up to 210 C., not more than 10% b. Up to 235 C., not more than 40% 6. A. W. P. A.

(1. Up to 210 C., not more than 5% b. Up to 235 C., not more than 15% 7. Prussian Ry.

a. Up to 150 C., not more than 3% b. Up to 200 C., not more than 10% 0. Up to 235 C., not more than 25% 8. N. P. V. & L. A. #220 a. 5% at 162 C. b. 97% at 270 C. 9. S. P. S. S. O.

a. 5% at 137 C. b. at 257 C. 10. N. S. S. O.

a. I. B. P., C. b. 5% at 205 C. c. 95% at 292 C. 11. Carbolineum 270 C., I. B. P.

The abbreviations shown in the foregoing are explained as follows: A. W. P. A., American Wood Preservers Association; N. S. S. 0., Neville Shingle Stain Oil; S. P. S. S. 0., Southern Pine a. b. 2. A.

Shingle Stain Oil; N. P. V. & L. A., National Paint, Varnish & Lacquer Association.

Example 4.As another illustrative embodiment of the present invention, a coal tar having a coke residue in excess of and approximately 1.5% boiling at 210 C. and approximately boiling at 270 C. and yielding a distillate at 355 C. which boils approximately 45% at 270 C., is charged to a still with 16% of its weight of a fraction of petroleum boiling above the gasoline range, and distilled. The distillation is carried to any desired point as for instance of 355 C. or above. If desired, the high point of distillation, is determined by the character of the still residual.

The vapors are conducted to a heating chamber having a capacity of the evolved vapors. The vapors while traversing the heating chamber are heated by any convenient method to from 300 C. to 750 C. The vapors, after having traversed the heating chamber are condensed to provide a product capable of yielding a wood preservative according to a specification selected from those cited supra or any desired specification. In the event the condensed product contains non-permissible low ends, they may be stripped and discarded insofar as the wood preservative is concerned; said stripped low ends may be used as solvents. The newly formed oil boiling between substantially 210 C. and 235 C.the desired wood preserver in this casehas an increment of fractions induced by the treatment described, boiling up to 270 C., with the added advantage of induced toxicity in the newly formed oil.

Instead of operating as described the entire condensed product may be used as a wood preservative, Without removal of especially low boiling ends, if formed, whereby to conform to some desired specification of a Wood preservative. In any proposal to use the new product, either as such, or fractionated to provide one or many possible wood preservatives, it will be found that the new product is more toxic to wood destroying fungi than the starting material.

Concerning the application of heat to the heating chamber, reference has been made to the range of from 300 to 750 C. It is, of course, impossible to state the temperature as an arbitrary figure, inasmuch as there is a great variance in the possible starting materials; however, a few trials will readily determine the proper selection of a temperature within the range of 300 C. and 650 C. or 750 C.

It may be noted that two low a temperature on a given feed stock will result in areduced toxicity, rather than an increase of toxicity. Too low a temperature will result in a too great percentage of .the stated petroleum or nontoxic fractions appearing in the condensed product as a parafiinic fraction, whereas the correct temperature in the heating chambers will result in the formation of a new oil of newly induced toxic characteristics with the attendant production of olefinic gas which may, with or without subsequent purification be used for the production of ethyl alcohol, ether or acids.

Too low a temperature in the heating chamber, even though the condensed product shows an increment of fractions boiling up to 270 C. as compared with the tar or fraction thereof, will indicated by actual test a decreased toxicity due to paraffinic fractions, whereas the correct temperature will show an increase of toxicity.

Among other things, the present invention is concerned with the distilling of a tar or tar product having a deficiency of hydrogen and toxicity with an oil having a richer content of hydrogen, subjecting the vapors to a temperature of between 300 C. and 650 C. or 750 C., whereby to induce toxicity in and add hydrogen to said tar or tar product at the expense of said oil relatively richer in hydrogen and whereby to convert a portion of the remainder of the oil relatively richer in hydrogen to lower boiling products, including gases.

Heat conditions are impressed on the vapors traversing the heating chamber to the end that wood preserving oils of added toxicity, and not illuminating oils in the true sense, are formed, which condition is, however, postulated among other things on the correct percentage of the oil rich in hydrogen having been added prior to distillation and the time of retention and temperature of the vapors in the heating chamber. Even as low as two, three or four per cent or more of said oil rich in hydrogen will prove beneficial to the end that useful toxicity be induced. In the absence of substantially superatmospheric pressure, the size of the heating chamber will, among other things, determine the time or retention of vapors.

By the correct co-ordination of proportion of oil of relatively high hydrogen content added, temperature in the heating chamber, times of retention of evolved vapors in said heating chamber, with or without pressure, the starting material, be it tar or a tar derivative, may have toxicity added thereto, whereby to serve, as such, as a wood preservative, or as a material to be fractionated to produce any desired specification of wood preservative.

If desired, the added oil relatively rich in hydrogen may have a boiling range, under the conditions of the aforesaid distillation, which extends over the entire boiling range of the tar or tar derivative. However, this is not essential and the boiling range may cover only a portion of the boiling range of the tar or tar derivative.

Instead of premixing the tar or tar derivative and oil relatively rich in hydrogen in a common still, and distilling the mixture, their distillations may be carried out in separate vessels and their vapors then subsequently mixed while traversing a common heating chamber.

The use of catalysts has the effect of smoothing out operation and providing better recoveries, but, as stated, is not essential to the practice of the invention.

Another method of practicing the present invention is to distill tar for the recovery of, as

for instance, grade 1 creosote. When said grade 1 creosote has been recovered, the remaining volatiles in the tar, or a selected portion thereof,

may be made to traverse a heating chamber as described supra, with the provision for and of vapors from an oil rich in hydrogen as previously described, being co-mingled in the heating chamber with the said high boiling vapors from said tar. The temperature in the heating chamber, time of retention of vapors in the heating chamber, with or without pressure, and the percentage of vapors of the oil relatively rich in hydrogen supplied from an extraneous source, are co-ordinated to the extent that the high boiling tar vapors are converted, modified, refined, saturated or partially saturated to the extent desired whereby to induce toxicity; by which statement is meant that said high boiling tar vapors may be reformed, saturated or partially saturated to the extent that they provide a boiling range, as for instance such as commonly described for carbolineum, or other desired wood preservatives; or the said high boiling tar vapors may be reformed, modified, saturated or partially saturated to provide a material suitable for admixture with a naturally recovered grade 1 creosote or other preserving oils, thus providing an oil of newly induced toxic characteristics.

Fractions of a wood preserving oil boiling above 270 C. have toxicity, but as their boiling range ascends and their carbon content increases, their toxicity approaches zero. Thus, in the foregoing example, the high boiling tar fractions held under conditions to effect modification, reformation, saturation or partial saturation, need not be so treated as to induce fractions boiling below 270 C.-yet they may-inasmuch as a primary consideration of the present invention, among other things, is the inducing of toxicity, and such does not necessitate the production of fractions boiling at or below 270 C.

In an example of practicing one productional method of the invention, reference was made to the supply of vapors evolved from an oil relatively rich in hydrogen, secured from an extraneous source as compared to the source of the high boiling tar vapor. As an alternative method, an oil relatively rich in hydrogen may be placed in the still with the tar, the oil relatively rich in hydrogen having an initial boiling point under the conditions of distillation, which includes its partial pressure under said conditions, so that no substantially great percentage of the vapors of the oil relatively rich in hydrogen are evolved until after the grade 1 creosote, or any grade selected has been driven 011 by distillation. After the vapors of said desired grade of creosote have been substantially evolved, the oil rich in hydrogen, because of the selected characteristics and conditions, may start to distill coincidentally with the heavier tar fractions. Such distillation having started, the combined vapors of the high boiling tar fractions and the oil relatively rich in hydrogen are led to a heating chamber, as described supra, where impressed conditions induce toxicity.

The present invention is especially adapted to the treating of high boiling residues from coal tar, or fractions thereof including creosote. Wax oil may also be treated by the process.

If desired, inert gases may also flow to the heating chamber with the aforenamed vapors for the purpose of, among other things, thermal protection to the high boiling tar vapors, or to reduce the percentage of hydrogen donor and hydrogen acceptor.

Another method of practicing the invention is to feed the correct proportions of the tar derived oil and the oil relatively rich in hydrogen to a heating coil under desired pressure, and to subsequently flash the vapors for delivery of same to aforementioned heating chamber; or the tar product may be placed in a still and distillation started and simultaneously the correct proportion of oil relatively rich in hydrogen may be injected into the still, the injection being made either above or below the liquid charge in the still. The thus evolved combined vapors may be handled as taught in the foregoing. Based on the starting tar, or fractions thereof, 5 to 10% up to volume for volume or more of the oil rich in hydrogen may be added.

In'all the foregoing examples may be incorporated the step of passing the vapors and/or condensed product issuing from the heating chamber to a dephlegmator. The condensate produced therein may be returned to the still while the non-condensed vapors are led to a condenser for the purpose of condensing the products having desired boiling ranges.

Any convenient means for supplying a constant production of vapors of said oil relatively rich in hydrogen may be practiced, as for instance, but not in a limiting sense, constant injection of said oil relatively rich in hydrogen into any desired zone of the still, as above or below the liquid charge; said injection being initially in liquid or vapor phase.

Another especial exemplification of practicing the present invention is in the joint production of solvents and wood preservatives of predetermined boiling range.

Example 5.--A coal tar, specific gravity 1.1641 and boiling predominantly above 190 C. is mixed with 20% of its weight of a petroleum distillate having residue above 380 C., the mixture is distilled to substantial dryness with the vapors therefrom being conducted to a toxicity inducing chamber heated to a temperature chosen between the range of 400 C. and 750 C.; the time of retention of said vapors in the toxicity inducing chamber is so controlled as to induce in the newly formed fractions a low boiling point of below 150 C. The low boiling fractions are characterized by a substantial aromaticity. The vapors flowing from the toxicity inducing chamber are condensed and fractionally cut at 270 C. to provide the low boiling portion as a solvent having superior solvent powers as compared to solvents extant of comparable boiling. The portion of above 270 C. serves as the wood preservative of enhanced toxic properties as compared to its parent materials.

When producing solvents and wood preservatives as mentioned in the paragraph supra, the point of fractionation between the solvent and the wood preservative is not an inflexible point. Inasmuch as the end point of the solvent substantially corresponds to the initial boiling point of the wood preservative, and inasmuch as solvents of present manufacture have varied and boiling points, and Wood preservatives of consumer acceptance have varied initial boiling points, it will be immediately obvious that the point of fractionation is not inflexible, but may be varied at will.

In the tabular data shown below are initial boiling points and end boiling points of wood preservatives and solvents of current acceptance, respectively, substitutes for which may be supplied by the process of the invention.

SOLVENTS Identification: End point Benzol C. Toluol C. High flash naphtha 200 C. Heavy naphtha above 200 C.

Woon PRESERVATIVES Identification: Initial point A. W, P, A 5% at 210C. A. W. P. A 1% at 210 C. A. W. P. A l /Z% at 210C. A. W, P,A 10% at 210 C. Prussian Ry 3% at 150 C. N. S. S. O 150 C. S. P. S. S. O 92 C. Carbolineum 270 C.

Example 6.A synthetic coal tar of petroleum origin and having the following inspection Gravity 10.8 Flash, P. M. C. C., deg. F 295 Flash, C. O. C., 290 Fixed carbon, percent 4.9 Pour point, deg. F 10 B. S. & W., percent by vol 0.1 S. U. Vis. 100 deg. F 151 S. U. Vis. 210 deg. F 41 S. F. Vis. 77 deg. F 34.5 Carbon residue 6.8 Percent aromatics 8; unsaturates (BPM) 84.4 Sol. in carbon bisulfide 99.8 Loss, 50 grams, hours, 3'25 deg. F 8.9 Residue of 100 pene., percent 37.5 A. S. T. M. distillation".

I. B. P., deg. F 518 565 20% 589 30% 614 40% 637 50% 660 60% (Max) 675 is mixed with 18% of its weight with a petroleum distillate having a residue above 340 C. and having a higher content of hydrogen than the petroleum aromatic. The mixture of oils is distilled to substantial dryness and the eiiieunt vapors led to a toxicity inducing chamber wherein the temperature is selected between the range of 400 C. and 750 C. .The time of retention of the vapors in the toxicity inducing chamber is so controlled as to induce a low boiling point of below 100 C. The condensed vapors flowing from the toxicity inducing chamber are fractionally cut at 210 C. to provide the lower boiling fraction thereof as a solvent of superior solvency, and high boiling portion thereof as a wood preservative of induced toxicity.

Another form of practicing the present invention provides for the recovery of only solvents from oils of the type of the synthetic coal tar above described. In this instance, the synthetic coal tar oil is mixed with a predetermined portion of an oil relatively rich in hydrogen distilled to an upper boiling point such that the vapors evolving from the distillation, after treatment in the thermal chamber, will contain a newly formed solvent of substantial aromatic content.

Example 7 .In the foregoing have been shown various means of practicing the process wherein the vapors were segregated from the parent material and subjected to a heat treatment. stead of practicing the process in the manner described, that is to say, by subjecting only the vapors to the heat treatment, the starting material may be partially vaporized and the entire material, vapors and liquid, simultaneously and in a common retainer subjected to thermal treatment.

As exemplifying this mode of operation a mixture of tar fractions of aromatic content, as for instance but not in a restrictive sense, a mixture of high temperature coal tar fractions relatively poor in hydrogen and boiling only 20% below 355 C. and. having a coke residue in excess of is mixed with a petroleum oil relatively rich in hydrogen having at least some portion thereof boiling within the range of said tar fractions, the percentage of mixture being, as an example, '10 parts of tar fractions and 30 parts petroleum oil. The mixture is passed through a heating coil and heated to a temperature selected between the range of 400 C. and. 750 0., as for example within the range of 450 C. to 575 C. The mixture passing through the heating coil'has a considerable portion thereof existing in the vapor phase. As the feed stock traverses the heating coil pressures of at least slightly above atmospheric may be employed. However, pressures of 20 atmospheres or in excess thereof provide advantageous practice of the process. For example, pressures between the range of and 1000 atmospheres may be usefully employed and pressures as high as obtainable at times are usable.

The time of treatment in the heating coil may vary over a wide range according to the charactertistics of the charging stocks, the conversion desired and percentage of mixtures employed. With any given mixture of charging stocks a few trials will readily determine the time element. Instead of employing a petroleum oil relatively rich in hydrogen as noted in the instant example, or in previous examples, any hydrocarbon relatively rich in hydrogen and conforming in boiling range to the foregoing teachings may be employed, as for instance, synthetic hydrocarbons, reaction products, distillation products of bituminous materials, distillation products of shale; distillation, extraction, conversion, or reaction hydrogenation products of bituminous materials, various oils, gases and conversion products thereof.

After the heat treatment of the mixture of feed stocks the reformed mas is then cooled to condense all vapors while yet in the tube or the reformed mass may be sent in heated condition to a soaking or digesting tank operated at elevated temperature where further reforming may take place, which may or may not be operated at the heating tube pressure. In the digesting tank, if used, free carbon, if any, may be allowed to settle out. The reformed mass, including permanent gas if desired is cooled as removal is effected from the digesting tank and the reformed oil stripped, if necessary, of a required percentage of low boiling fractions whereby to provide as the stripped high boiling portion an oil of the wood preserving type having no greater percentage of fractions boiling below a specified temperature, nor a greater percentage of material boiling between initial point and a specified temperature than is permitted by specifications accepted in the trade for a tar derived wood preservative, as for instance, an A. W. P. A. wood preservative, or others. However, the wood preservative may be recovered as a distillate conforming to specifications extant.

V In the event the mixture of raw starting stock is passed through the heating coil without re"- course to the digesting tank, the reformed materials are preferably cooled while yet under presof passing the vapors to a toxicity inducing chamher. The heat treatment in (1) the heating coil, or (2) the heating coil and digesting tank is effected, at least to a degree, in the vapor phase.

The pressure in the heating coil and/or digesting tank may be autogenous or the pressure may at least to a degree, be secured by added hydrocarbon gas or gases, hydrogen or the like, as for instance any non-oxidizing gas including steam. The added gas or gase may-take part in the reaction.

or, higher.

When passing the heated mixture of crude feed stocks through the heating coil it is advisable at times to pass the feed at a high rate through the coil in order to prevent insofar as possible polymerizing or coking action.

Viewed broadly, the low limit of temperature usable in the reforming, conversion or modification step is that temperature which produces at least incipient cracking.

In the selection of percentages of the oil rich in hydrogen to be employed a few trials with any mixture of tar fractions to be reformed, converted or modified will show the most effective percentage. Any hydrocarbon relatively rich in hydrogen and liquid at operating temperatures may be employed. The oil relatively rich in hydrogen is circumscribed by the limitation that it must have at least a boiling point thereof which conform to a boiling point of the mixture of tar fractions to be converted, modified or reformed.

When practicing the process in accordance with the instant example the charging stocks undergoing reformation, conversion or modification .may exist at some time in (1) the vapor phase,

(2) hybrid phase, that is to say liquid and vapor phase, or (3) vapor, liquid and solid phase. By the term solid phase is meant to designate polymerized products which cannot be considered liquid products.

In the instant example, steps or combinations of steps described in the foregoing examples may be employed.

Catalysts may be employed in the instant example, as in all examples of practicing the process, among which may be mentioned substances favoring thermal splitting such as oxides, sulphides, metals or metal compounds, phosphates, sulphates, carbonyls, separately or in admixture. Among these and other catalyst that are especially effective may be mentioned copper, tin, manganese, vanadium, iron, nickle, cobalt, chromium, molybdenum and tungsten, as for instance their oxides and/or sulfides. Also especially effective as catalytic materials may be employed halogens, halids, and derivatives thereof, or material furnishing under the reaction conditions the equivalent thereof. It is well known in the art that varying percentages of catalytic materials may be employed. This is too well known in the art to need further discussion here.

Example 8.-As a variation of the process described in Example 7 a very attractive form of practicing the present invention is the production of solvents a hereinafter described. Mix

50 parts of a predominantly parafiinic oil of petroleum origin relatively rich in hydrogen and having at least a portion thereof boiling as high as 355 C. with 50 parts of a coal tar distillate relatively poor in hydrogen and boiling preponderantly above 355 C. The mixture is passed through a heating coil and heated to a temperature of 490 C. the while maintaining a pressure of 500 atmospheres. A portion of the feed stock is vaporized. The heat treated material is cooled to atmospheric temperature while yet under pressure if desired and upon inspection will be found to have newly formed fractions of aromatic content. The overall material is an excellent solvent for many purposes, or the overall material may be fractionated to provide solvent of varying boiling ranges. Pressures of above 20 atmospheres in the instant solvent example are preferred, as for example, 100, 200, 500 atmospheres Temperatures selected from a range of 400 to 750 C. serve the proces purpose.

Various changes may be made in the details disclosed in the foregoing within the scope of the appended claims, without departing from the spirit of the invention or sacrificing the advantages thereof.

I claim:

1. In the production of wood preservative the process which comprises: mixing fractions of toxic coal tar with a substantially non-toxic petroleum oil; vaporizing at least a portion of said mixture and subjecting the mixture of said materals substantially in entirety to heat treatment at a temperature of from 300 C. to 750 C. and condensing the vapors; controlling the time and temperature of heat treatment and percentage of non-toxic oil so that the overall liquid reaction product is an oil of the wood preserving type boiling not in excess of about 3% at C.

2. In the production of wood preservative the process which comprises: mixing fractions of toxic coal tar with substantially non-toxic petroleum oil; subjecting the mixture of said materials in substantial entirety to heat treatment at a temperature from 300 C. to 750 C. whereby to vaporize at least a portion thereof and to induce toxic properties; condensing said vapors and stripping from the overall reformed prodnot a percentage of low boiling materials whereby to provide the stripped residual as an oil of the wood preserving type having not in excess of 3% boiling at 150 C.

3. In the production of wood preservative the process which comprises: mixing fractions of toxic coal tar with a substantially non-toxic petroleum oil relatively rich in hydrogen; subjecting the mixture of said materials in substantial entirety to heat treatment at a temperature from 300 C. to 750 C. whereby to vaporize at least a portion thereof and to induce toxic properties; condensing vaporous material and recovering from the overall heat treated product a distillate of the wood preserving type boiling not in excess of 3% at 150 C.

4. In the induction of toxicity the process which comprises: mixing a substantially nontoxic petroleum oil with carbonaceous material containing condensed ring structures; subjecting the mixture of said material in substantial entirety to a heat treatment at a temperature of from 300 C. to 750 C. whereby to vaporize at least a portion thereof and condensing the vapors; controlling the time and temperature of heat treatment and percentage of non-toxic petroleum oil so that the overall liquid reaction product is an oil of the wood preserving type bolling not in excess of about 3% at 150 C.

5. In the induction of toxicity the process which comprises: mixing a substantially nontoxic petroleum oil with carbonaceous material containing condensed ring structures; subjecting the mixture of said materials in substantial entirety to heat treatment at a temperature of from 300 to 750 C. whereby to vaporize at least a portion thereof and to induce toxic properties; condensing the vapors and stripping from the overall reformed product a percentage of low boiling materials whereby to provide the stripped residual as an oil of the wood preserving type having not in excess of about 3% boiling at 150 C.

6. In the induction of toxicity the process which comprises: mixing a substantially nontoxic petroleum oil with carbonaceous material containing condensed ring structures; subjecting the mixture of said material in substantial entirety to a heat treatment at a temperature selected from the range 300-750 C. whereby to vaporize at least at least a portion of the material and to induce toxic properties; condensing vaporized. material and recovering from the overall heat treated product a distillate of the wood preserving typ having not in excess of about 3% boiling at 150 C.

7. In the production of a wood preservative the process which comprises: mixing fractions of toxic tar with a relatively non-toxic petroleum product; vaporizing at least a portion of said mixture; subjecting said vaporous material to heat treatment at a temperature of from 300 C. to 750 C. and condensing the vapors; controlling the time and temperature of vapor heating and petroleum product percentage so that the condensed product boils not more than 3% at 150 C. whereby to induce toxic properties and provide a material toxic to wood destroying agencies.

8. In the production of a wood preservative the process which comprises: mixing fractions of toxic tar with relatively non-toxic petroleum fraction; vaporizing at least a portion of said mixture and subjecting said vapors to heat treatment at a temperature of from 300 C. to 750 C. whereby to induce toxic properties; condensing said vapors and stripping the condensate of low boiling ends to leave not substantially more than 3% distilling at 150 C.

9. The process of claim 7 with inclusion of passing the material in vaporous phase over contact material.

.10. The process of claim 8 which includes the passing of the material in vaporous phase over contact materials.

11. The process of claim 7 with inclusion of the step of returning a portion of the product once subjected to toxicity inducing conditions for treatment under further toxicity inducing conditions.

12. The process of claim 8 with inclusion of the step of returning a portion of the product once subjected to toxicity inducing conditions for retreatment under toxicity inducing conditions.

13. In the inducing of toxicity the process which comprises: mixing a relatively high boiling and substantially non-toxic petroleum product with carbonaceous material containing condensed ring structures; vaporizing at least a portion of said mixture and subjecting said vapors to a heat treatment at a temperature of from 300 C. to 750 C. whereby to induce toxicity;

condensing said vapors to provide a toxic product boiling not substantially more than 3% at C.

14. In the inducing of toxicity the process which comprises: mixing a relatively high boiling and non-toxic petroleum product with a carbonaceous material containing condensed ring structure; vaporizing at least a portion of said mixture and subjecting said vapors to a heat treatment at a temperature of from 300 C. to 750 C. whereby to induce toxicity; condensing said vapors and stripping the condensed product of low boiling ends to provide a product boiling not more than 3% at 150 C. having induced toxic properties.

JACQUELIN E. HARVEY, JR. 

